Pac-12 football: Chip Kelly leaves Oregon for the NFL

If you haven’t heard: CK’s gone, just as many of us expected … except not in the manner anyone expected … after he turned down initial options and the Ducks announced he was staying put … and then reversing his course like DAT … and heading to Philadelphia, which was considered the leader in the clubhouse when this whole thing began weeks ago.

Got it? If not, don’t worry: Everything with Kelly is fast and tough to follow.

Insta-reaction in brief, because I have to attend a 49ers press conference in an hour:

* Shock and deep disappointment in Eugene and all points beyond occupied by Oregon fans; celebrations everywhere else in the Pac-12 footprint.

* Will Kelly’s system work in the NFL?

The Ducks, after all, struggled against the closest thing to NFL defenses that they faced the past few years (Auburn, LSU, Stanford).

Kelly will have to make significant tweaks. He knows that and, I’m sure, has already thought it through 10 times over.

The pace with which his offense plays will have to change. Because of roster limitations and the grind of a 16-game season (plus exhibitions and playoffs), Kelly simply cannot ask his defense to be on the field for 34+ minutes week after week.

The Eagles won’t have anything left by Dec. 1.

But I think he’ll be successful — not a great NFL coach but a good one.

* I’m assuming that the Ducks will follow through with their plans to promote offensive coordinator Mark Helfrich, although that’s not official yet.

* It’s only natural to compare the situation to that of Oregon’s nemesis in the North: Stanford, which lost its head coach to the NFL two years ago and hired from within (with a fair amount of success, I’d say).

But there is a difference between David Shaw taking over for Harbaugh and Helfrich replacing Kelly, and here it is:

Oregon’s system is more closely tied to Kelly than Stanford’s system was to Harbaugh.

Shaw spent nine years in the NFL and has long been an advocate of the pro-style power game, which uses principles of the west coast offense (think: play-action, tight ends and fullbacks). Heck, he played for the creator of the west coast offense: Bill Walsh.

Shaw also worked closely with Harbaugh to devise, implement and recruit to the system when Harbaugh took the Stanford job in Dec. ’06, with Shaw joining him from the University of San Diego.

How does that contrast to the situation at Oregon?

Helfrich joined the staff in 2009 when CK took over as head coach and he is well respected within the coaching community.

But the Quack Attack is Kelly’s baby all the way — in a manner that few coaches in major college history have owned a scheme and philosophy.

Oregon will be losing more of its essence with Kelly’s departure … more of its system and its culture … than Stanford did when Harbaugh left.

That doesn’t mean the Ducks cannot remain an elite program in the post-Kelly era or that Helfrich won’t equal, or better, Shaw’s initial success (two-year record: 23-4). They have so much momentum, so many resources and so much talent.

But on an intermediate- and long-term basis, I wonder if the change will be as smooth as it was with their North nemesis.